FR3119409A1 - Electronic lock cylinder - Google Patents

Abstract

Electronic lock cylinder This electronic cylinder comprises a protection circuit (110) comprising: - a switch (Q4) comprising a control terminal (112) and two power terminals (114, 116), the two power terminals being electrically connected , respectively, to an electrical contact (101) of the cylinder and to a supply port (204) of a microcontroller (200), this switch being capable of switching in response to the reception of an insulation command on its control terminal: - from a closed state in which it electrically connects the electrical contact (101) to the power supply port (204), - to an open state in which it electrically isolates the electrical contact from the power supply port, and - an insulation command generator (130) capable of generating and transmitting the insulation command to the control terminal of the switch when the voltage between electrical contacts (101, 102) exceeds a predetermined threshold. Fig. 4

Description

Electronic lock cylinder

The invention relates to an electronic lock cylinder.

There are electronic lock cylinders which are powered by a battery housed inside the key introduced into this cylinder. Such a cylinder is for example disclosed in application EP3431684. This type of cylinder is particularly advantageous in that it does not require the electronic cylinder to be connected to a power supply network. It is also not necessary to supply it from an internal battery to this electronic cylinder. Problems related to the replacement of this internal battery are therefore also avoided.

To this end, the known cylinders comprise at least two electrical supply contacts which come into mechanical and electrical contact on corresponding electrical contacts arranged on the blade of the key inserted inside this cylinder. These electrical power contacts therefore make it possible to establish two electrical connections which electrically connect the electronic cylinder to the battery housed inside the key to power it. This power supply to the cylinder is notably necessary to supply a microcontroller and an electric actuator housed inside the cylinder. The microcontroller is typically used to manage the exchange of information between the cylinder and the key and to trigger the unlocking of the cylinder if the key inserted inside this cylinder is a key authorized to unlock it.

Currently, this type of cylinder is protected against the appearance of a temporary overvoltage between the two electrical supply contacts using a Zener diode connected between these two electrical supply contacts. A transient overvoltage is a voltage between the power supply electrical contacts that exceeds the microcontroller's maximum supply voltage for a fraction of a second. This Zener diode makes it possible to clip these temporary overvoltages and thus prevent the destruction of the microcontroller.

On the other hand, it has been observed that such a Zener diode does not make it possible to protect the microcontroller of the cylinder against permanent overvoltage, that is to say against overvoltage present between the electrical contacts. supply as long as the key remains inserted inside this cylinder. Such a permanent overvoltage is for example caused by the fact that the battery housed inside the key has a nominal voltage higher than the nominal voltage provided for this battery. In particular, it has been observed that even if the permanent overvoltage is only slightly higher than the expected nominal voltage of the battery, it could still lead to the destruction of the cylinder's microcontroller. However, the destruction of the microcontroller generally leads to the destruction of the various information recorded in this microcontroller.

The invention aims to remedy this drawback by proposing a cylinder that is more robust both with respect to temporary overvoltages and permanent overvoltages. It therefore relates to such an electronic lock cylinder comprising:
- a reversibly movable blocking member between:
- a locking position in which it locks the electronic cylinder, and
- a retracted position in which the electronic cylinder is unlocked,
- an electric actuator capable of moving the blocking member from its blocking position to its retracted position in response to receiving an unlocking command,
- a first and a second electrical contact capable of coming directly into electrical and mechanical contact on, respectively, first and second electrical contacts of a key inserted inside the electronic cylinder, to power the electronic cylinder from a battery housed inside the key,
- a microcontroller configured to determine whether the key introduced into this electronic cylinder is a key authorized to unlock this electronic cylinder and, only if so, to transmit the unlocking command to the electric actuator, this microcontroller comprising a first and a second power supply ports electrically connected, respectively, to the first and second electrical contacts of the electronic cylinder,
- a microcontroller protection circuit against an overvoltage applied between the first and second electrical contacts,
wherein the protection circuit comprises:
- a first switch comprising a control terminal and a first and a second power terminal, the first and the second power terminal being electrically connected, respectively, to the second electrical contact of the cylinder and to the second power supply port of the microcontroller, this first switch being able to switch in response to the reception of an isolation command on its control terminal:
- from a closed state in which it electrically connects the second electrical contact to the second power supply port of the microcontroller,
- to an open state in which it electrically isolates the second electrical contact from the second power supply port of the microcontroller, and
- an insulation command generator capable of generating and transmitting the insulation command to the control terminal of the first switch when the voltage between the first and second electrical contacts exceeds a first predetermined threshold.

Embodiments of this electronic cylinder may include one or more of the following features:
1) the insulation control generator comprises a diode whose cathode is connected to the first electrical contact, this diode being capable of switching when the voltage present between the first and second electrical contacts exceeds the first predetermined threshold:
- from a non-conducting state in which it inhibits the generation of the isolation command,
- To an on state in which it triggers the transmission of the insulation command on the control terminal of the first switch.
2) the generator includes:
- a first and a second resistor connected in series between the anode of the diode and the second electrical contact, and
- a second switch comprising:
- a control terminal connected to a midpoint located between the first and second resistors,
- a first power terminal connected to one of the first and second electrical contacts, and
- a second power terminal connected to the control terminal of the first switch,
this second switching switch, when the midpoint voltage exceeds a second predetermined threshold:
- from an open state in which it inhibits the transmission of the insulation command on the control terminal of the first switch,
- Towards a closed state in which it transmits the insulation command to the control terminal of the first switch.
3) the actuator comprises first and second power supply terminals electrically connectable, respectively, to the first and second electrical contacts, the second power supply terminal of the actuator being electrically connected to the second electrical contact via the first protection circuit switch.
4) the first switch is capable of withstanding the application of a DC voltage greater than 50 Vdc between the first and second electrical contacts.
5) the cylinder comprises:
- a third electrical contact capable of coming directly into electrical and mechanical contact with a third electrical contact of the key inserted inside the electronic cylinder, to establish an electrical connection via which the cylinder and the key exchange information , And
- A diode whose cathode is connected to the first electrical contact and whose anode is connected to the third electrical contact.

The invention will be better understood on reading the following description, given solely by way of non-limiting example and made with reference to the drawings in which:
- there is a schematic illustration of a door equipped with an electronic cylinder;
- there is a schematic illustration, in perspective, of an access control system comprising the cylinder of the and a key;
- there is a schematic illustration, in vertical and longitudinal section, of the electronic cylinder of the ;
- there is a schematic illustration of part of an electronic circuit implemented in the electronic cylinder of the system of the .

In these figures, the same reference numerals are used to designate the same elements. In the remainder of this description, the characteristics and functions well known to those skilled in the art are not described in detail.

In this description, detailed examples of embodiments are first described in a chapter I with reference to the figures. Then, in a chapter II, variants of these embodiments are presented. Finally, the advantages of the different embodiments are presented in a chapter III.

Chapter I: Examples of embodiments

Figure 1 shows a door 2 for access to a building. This door 2 has an interior side, typically located inside a room, and an exterior side on the opposite side. Hereafter, the terms “interior” and “exterior” refer, respectively, to the interior and exterior sides of the door 2. The door 2 here extends in a vertical plane. Thereafter, the vertical direction is designated by the Z direction of an XYZ orthogonal frame. The direction X is perpendicular to the vertical plane in which the door 2 mainly extends. All of the figures in which mechanical components are shown are oriented with respect to this reference XYZ.

Door 2 is equipped with a handle 4 and an electronic lock 6. To simplify Figure 1, only part of door 2 is shown.

The general mechanical architecture of lock 6 is, for example, identical to that described in applications FR3025236 and EP3431684. For this reason, only the details necessary for understanding the invention are given here. For further details, the reader is referred to these requests.

The lock 6 comprises a bolt 10 movable in translation, parallel to the direction Y, alternately and reversibly, between an extended position and a retracted position. In the extended position, the bolt 10 protrudes beyond the edge of the door 2 to engage in a keeper fixed without any degree of freedom on the frame of the door 2. In the extended position, the bolt 10 locks door 2 in its closed position. In the retracted position, the bolt 10 is retracted inside the door 2 and no longer protrudes beyond the edge of this door 2. In the retracted position, the door 2 can be moved by a user of a closed position to an open position by operating the handle 4.

The lock 6 also includes an electronic cylinder 12 and a screw 14 for fixing the cylinder 12 in the door 2.

The cylinder 12 is movable between an unlocked position and, alternately, a locked position. In the unlocked position, it authorizes the opening of the door 2 and therefore access to the building. In the locked position, it prohibits the opening of the door 2 and therefore access to a building. For this, the cylinder 12 moves the bolt 10 from its extended position to its retracted position when a key 16 (FIG. 2), authorized to unlock the lock 6, is inserted, then turned inside this cylinder 12. The cylinder 12 also moves the bolt 10 from its retracted position to its extended position when the authorized key is introduced and then turned in the opposite direction inside this cylinder. Conversely, when an unauthorized key is introduced inside the cylinder 12, this cylinder prevents the movement of the bolt 10 from its extended position to its retracted position.

Here, the key 16 can be introduced inside the cylinder 12 from the exterior side and, alternately, from the interior side of the door 2. For this purpose, the cylinder 12 emerges on each side of the door 2.

Screw 14 has a head that is flush with the edge of door 2. The threaded end of screw 14 is screwed into cylinder 12 to hold it in place inside door 2.

Cylinder 12 has no internal power source. In particular, it lacks:
- a battery capable of storing enough energy to allow the cylinder 12 to switch more than a hundred times between its unlocked and locked positions without an external energy supply, and
- A mechanism capable of generating enough electricity to move the cylinder 12 into its unlocked position from, for example, the movement of the key inside the cylinder.

Figure 2 shows in more detail the access control system produced using the lock 6 and the key 16.

Here, cylinder 12 conforms to the European format. The cylinder 12 extends along a longitudinal axis 20 parallel to the direction X. It comprises a stator 22 fixed without any degree of freedom to the door 2 by means of the screw 14 and a bit 24 housed at the inside a transverse notch 26.

The notch 26 extends in a transverse plane 28 parallel to the directions Y, Z. Here, only part of the plane 28 is shown in Figure 2. The plane 28 is a plane of symmetry for the bit 24.

The bit 24 rotates counterclockwise around the axis 20 to move the bolt 10 from its extended position to its retracted position and in the opposite direction to move the bolt 10 from its retracted position to its extended position.

The plane 28 also divides the stator 22 into two parts. The part of the stator 22 located on the inner side of door 2 is called "inner half-stator" and bears the reference 30. The part of stator 22 located on the outer side of door 2 is called "outer half-stator" and bears the reference the reference 32. In this particular embodiment, the half-stators 30 and 32 are almost symmetrical to each other with respect to the plane 28. Thus, only the half-stator 32 is described in more detail by the following.

The half-stator 32 comprises a front cover 34 parallel to the plane 28 and directly exposed outside the door 2. This front cover prevents having direct access to the moving parts located inside the cylinder 12 so as to protect them against break-in attempts. This cover 34 is crossed by an orifice 36 intended to receive a blade 38 of the key 16. The orifice 36 is centered on the axis 20. The orifice 36 is shaped so as to allow the introduction of the blade 38 to inside the cylinder 12 by a translation movement parallel to the direction X. The orifice 36 is also shaped to allow the key 16 introduced inside the cylinder 12 to turn on itself around the axis 20 .

Here, the key 16 is an electronic key capable of transmitting an access code to the cylinder 12 so that the latter, in response:
- authorizes the unlocking of cylinder 12 if the access code received is a valid access code which authorizes the key to open door 2, and alternately
- prohibits the unlocking of cylinder 12 if the access code received is an invalid access code which does not authorize the key to open door 2.

To this end, the key 16 comprises a transceiver 40 and a battery 41.

Here, the blade 38 has no pattern in relief intended to move the pins of the lock to cause mechanical unlocking of the lock 6. On the other hand, the blade 38 comprises at least one pattern capable of cooperating with a pattern of complementary shape on a rotor of cylinder 12 to drive this rotor in rotation when the key turns. Here, this pattern on blade 38 is a flat 42 located on its distal end.

The transceiver 40 is in particular capable of transmitting, via an electrical connection, the access code to the cylinder 12.

Battery 41 is used here to power cylinder 12 via electrical connections. These electrical connections are established only when the blade 38 is introduced inside the cylinder 12. For this purpose, the blade 38 comprises electrical contacts capable of cooperating with corresponding electrical contacts of the cylinder 12 to establish these electrical connections between the key 16 and the cylinder 12. By way of illustration, here, the blade 38 comprises six electrical contacts arranged symmetrically on either side of the axis of the blade 38. For example, the symmetrical contacts one of the other are part of the same conductive ring. In the figures, only the contacts 44 to 46 located on the same side of the blade 38 are visible.

FIG. 3 shows the inside of cylinder 12 in greater detail. Stator 22 comprises a cylindrical channel 50, of circular cross-section, crossing right through stator 22 and therefore the two half-stators 30 and 32. This channel 50 extends along the axis 20. Here, the axis 20 coincides with the axis of symmetry of revolution of the channel 50.

_{The channel 50 receives a rotor 52. The rotor 52 is for example identical to that described in more detail, in particular, with reference to FIGS. 5 and 6 of application FR3025236. In particular, the rotor 52 comprises a housing 96 capable of receiving the end of the blade 38. The cross section of this housing 96 comprises at least one shape complementary to the end of the blade 38 so as to be meshed in rotation by the blade 38. Here, this complementary shape is a flat capable of meshing with the flat 42 of the blade 38. Thus, when an authorized key is turned inside the lock 6, the rotation of the key 16 causes the rotation of the rotor 52 which itself causes the rotation of the bit 24.}

At its ends, channel 50 opens into cover 34 opposite orifice 36.

Here, the half-stator 32 comprises a shell 54 located entirely on the exterior side of the plane 28 and half of a strip 56 located on the exterior side of this plane 28. The strip 56 is symmetrical with respect to the plane 28.

The shell 54 includes the front cover 34, the orifice 36 and half of the channel 50 located on the exterior side. Preferably, the shell 54 is formed from a single block of rigid material. By “rigid material” or “rigid material”, is meant a material whose Young's modulus at 25° C. is greater than 100 GPa or 150 GPa and, preferably, greater than 200 GPa.

The half-stator 32 comprises a controllable mechanism 76 for unlocking the cylinder. This mechanism 76 is able to move a member 80 for blocking the rotation of the rotor 52. This mechanism 76 is fixed, without degree of freedom, on the shell 54. For example, the mechanism 76 and the member 80 are similar or identical. to those described in application FR3025236. To increase the readability of FIG. 3, the representations of the mechanism 76 and of the member 80 have been simplified.

The member 80 moves in translation between a locking position (shown in Figure 3) and a retracted position. In the blocking position, a distal end of the member 80 is received inside a crevice arranged in the rotor 52 to prevent the rotation of this rotor around the axis 20. In the retracted position, the distal end of the member 80 is located outside the crevice, so that the rotor 52 can be driven in rotation by the key 16 around the axis 20. For example, the member 80 moves only in translation between its blocking position and its retracted position. Here, this translational displacement is parallel to the Z direction.

The mechanism 76 typically comprises a controllable electric actuator 82 and an electronic unit 84 for controlling this actuator 82. Here, in response to an unlocking command transmitted by the unit 84, the actuator 82 moves from an active position to a idle position. In the inactive position, the member 80 can be freely moved from its locking position to its retracted position when the key 16 is turned inside the cylinder 12. In its active position, the actuator 82 holds the member 80 in its locking position. In the absence of an unlocking command, actuator 82 is in its active position and member 80 cannot be moved to its retracted position. Once the actuator 82 has reached its inactive position, it remains in its inactive position until the key 16 is removed from the cylinder 12. Typically, the actuator 82 is maintained in its inactive position without consuming energy. electric energy. For example, for this, it comprises a magnet mechanism which keeps it in its inactive position until the removal of the key 16. The displacement of the actuator 82 from its inactive position to its active position is here mechanically driven by the movement of the key when it is removed from the cylinder 12.

Unit 84 is suitable:
- to receive the access code transmitted by the key introduced into the cylinder 12, then
- Depending on the access code received, to transmit to the actuator 82 the unlocking command and, alternately, to inhibit the transmission of this unlocking command to maintain the member 80 in its locking position.

To authorize or, on the contrary, inhibit the transmission of the unlocking command, the unit 84 compares the access code received with pre-recorded access codes. If the access code received corresponds to one of the prerecorded access codes, then unit 84 transmits the unlock command. Otherwise, the unit 84 does not transmit this unlocking command.

Here, the unit 84 communicates with the transceiver 40 via an electrical link 106 which is established when the key 16 is completely inserted inside the channel 50. At the same time, the battery 41 transmits the energy required to power mechanism 76 via two electrical connections 107 and 108. Connection 106 is established via contact 44 and an electrical contact 100 of half-stator 32. Connections 107 and 108 are established via contacts 45, 46 and two electrical contacts 101 and 102 of half-stator 32.

_{The electrical contacts 100 to 102 are, for example, structurally identical to each other. For example, these contacts 100 to 102 are made as described in application EP3431684.}

There shows in more detail a circuit 110 which protects the unit 84 and the actuator 82 against permanent and temporary overvoltages applied between the electrical contacts 101 and 102.

Unit 84 comprises a microcontroller 200 and a transceiver 202 connected to the microcontroller 200.

In this text, unless otherwise specified, the term “connected” means “electrically connected”. In this text, the expression "directly connected" means that two electrical components are connected to each other, only by a wired connection and therefore without passing through another electrical or electronic component different from a wired connection.

Here, a wire connection or an electrical conductor is typically an electrical wire, for example of circular section, or an electrical track of a printed circuit.

The microcontroller 200 comprises two power ports 204 and 208 connected, respectively, to the electrical contacts 101 and 102 to power this microcontroller 200 using the electrical energy stored in the battery 41 of the key 16 when the electrical connections 107 and 108 are established.

Here, port 208 is connected to electrical contact 102 via a diode CR1 whose cathode is directly connected to port 208.

The cathode of diode CR1 is also directly connected to a voltage booster 260, the output of which is connected to an electrode 230 of a capacitor C3. The other electrode of capacitor C3 is connected to the ground of unit 84. The ground of unit 84 is floating as long as electrical connection 107 is not established. Once the electrical link 107 is established, in normal operation, the ground of the unit 84 is connected to the negative electrode of the battery 41 via the link 107.

Capacitor C3 is capable of storing enough energy to power actuator 82 so that it moves blocking member 80 from its blocking position to its retracted position.

The elevator 260 makes it possible to charge the capacitor C3 with a voltage higher than the voltage delivered by the battery 41 between the electrical contacts 101 and 102.

The electrode 230 is connected via a switch Q9 to a terminal 82A supplying the actuator 82. The other terminal 82B supplying the actuator 82 is connected to the mass of the unit. 84.

Switch Q9 has a control terminal 280 and two power terminals 282, 284. Terminal 282 is directly connected to electrode 230. Terminal 284 is directly connected to terminal 82A of actuator 82. Terminal 280 is directly connected to an output port 286 of microcontroller 200. Switch Q9 switches between a closed state and an open state. In the open state, it electrically isolates terminals 282 and 284 from each other so that actuator 82 is not powered. In the closed state, switch Q9 connects terminals 282 and 284 so that terminal 82A is connected to electrode 230 of capacitor C3. Thus, in the closed state, the switch Q9 enables the supply of the actuator 82 when the capacitor C3 is sufficiently charged. Switch Q9 switches from its open state to its closed state in response to the reception on terminal 280 of an unlock command. Here, this unlocking command is an electrical signal to close switch Q9. In the absence of a closing signal transmitted by the microcontroller 200, the switch Q9 is in its open state.

The microcontroller 200 comprises:
- a memory 216 which includes the instructions necessary to determine whether a key inserted inside the cylinder 12 is an authorized key or an unauthorized key to unlock this cylinder, and
- a microprocessor 218 capable of executing the instructions recorded in the memory 216.

The memory 216 includes in particular the instructions of an access control module 222. When the instructions of module 222 are executed by microprocessor 218, cylinder 12 interacts with key 16 to assess the validity of the access code transmitted by key 16.

The microcontroller 200 also includes a communication port 226 connected to the transceiver 202 to receive and transmit to the transceiver 202 baseband information. Transceiver 202 encodes the information and then transmits it over electrical link 106. Conversely, transceiver 202 decodes the information received via electrical link 106 and transmits the decoded information over the port. 226 of the microcontroller 200. For this purpose, the transceiver 202 is connected to the electrical contact 100.

The unit 84 comprises a circuit 110 for protecting the microcontroller 200 and the actuator 82 against overvoltages and, in particular, permanent and temporary overvoltages.

Circuit 110 includes a switch Q4 which makes it possible to electrically isolate port 204 and terminal 82B from electrical contact 101. Switch Q4 includes a control terminal 112 and two power terminals 114 and 116. Terminal 114 is directly connected to electrical contact 101. Terminal 116 is connected to port 204 and to terminal 82B of actuator 82.

Switch Q4 switches between a closed state and an open state in response to receiving an isolation command on its control terminal 112. In the open state, switch Q4 electrically isolates terminals 114 and 116. Thus, in the open state, microcontroller 200 and actuator 82 are electrically isolated from electrical contact 101. They are therefore protected against an overvoltage, even permanent, applied between the electrical contacts 101 and 102. Typically, in its open state, the switch Q4 is capable of withstanding, without suffering any degradation, a permanent overvoltage between the contacts 101, 102 greater than 50 Vdc and, of preferably greater than 100 Vdc or 150 Vdc. In the open state, the microcontroller 200 and the actuator 82 can no longer be powered and no longer operate. In the closed state, terminals 114 and 116 are connected to each other. Thus, in the closed state, in the presence of a normal voltage between electrical contacts 101 and 102, microcontroller 200 is powered and actuator 82 can operate. In particular, when the microcontroller 200 is powered, the microprocessor 218 executes the access control module 222.

Here, switch Q4 is an N-type MOSFET ( Metal Oxide Semiconductor Field Effect Transistor) transistor. Terminals 112, 114 and 116 therefore correspond, respectively, to the gate, source and drain of this transistor. This transistor also includes a protection diode 118 whose anode is directly connected to the electrical contact 101.

Due to the presence of diode 118, another N-type MOSFET transistor Q5 is connected in series with switch Q4. Transistor Q5 comprises:
- a control terminal 120 connected to the electrical contact 102 via the diode CR1,
- a power terminal 122 directly connected to the power terminal 116 of switch Q4,
- a power terminal 124 directly connected to port 204 and to terminal 82B, and
- a protection diode 126 whose cathode is directly connected to terminal 116.

Transistor Q5 electrically isolates port 204 and terminal 82B from electrical contact 101 when the voltage applied between electrical contacts 101 and 102 is negative. Such a situation can appear when the battery 41 of the key 16 is mounted upside down. In this case, the polarities applied to the electrical contacts 101 and 102 are reversed with respect to those provided during normal operation. Transistor Q5 prevents such upside-down mounting of battery 41 from damaging microcontroller 200 or actuator 82.

Circuit 110 also includes a generator 130 of the insulation command transmitted on terminal 112 of switch Q4. Generator 130 generates and transmits the insulation command on terminal 112 only when the voltage between electrical contacts 101 and 102 exceeds a predetermined threshold S1. Threshold S1 is equal to the maximum voltage or less than the maximum voltage that can be applied between ports 204 and 208 of microcontroller 200 without damaging this microcontroller. In this example, threshold S1 is equal to 4 Vdc. Below this threshold S1, generator 130 inhibits the transmission of the insulation command on terminal 112 of switch Q4.

In this exemplary embodiment, the generator 130 comprises successively connected in series between the electrical contacts 102 and 101:
- a Zener diode CR6, whose cathode is directly connected to the cathode of diode CR1,
- a resistor R8,
- a midpoint 132,
- a resistor R9,
- a diode CR4, whose anode is directly connected to resistor R9, and
- a diode CR5, the cathode of which is directly connected to the electrical contact 101.

Generator 130 also includes a switch Q1 and a resistor R1.

Switch Q1 comprises:
- a control terminal 136 directly connected to the midpoint 132,
- a power terminal 138 directly connected to terminal 112 of switch Q4, and
- a power terminal 139 directly connected to the electrical contact 101.

Terminal 138 of switch Q1 is also connected to the cathode of diode CR1 through resistor R1.

Switch Q1 switches from an open state to a closed state when the voltage on its terminal 136 exceeds a predetermined threshold S2. Threshold S2 is lower than threshold S1. Here, threshold S2 is equal to 0.55 Vdc. In its open state, switch Q1 electrically isolates terminals 138 and 139 from each other. The potential applied to terminal 112 of switch Q4 is then positive and greater than that of ground, which maintains switch Q4 in its closed state.

In its closed state, switch Q1 connects terminals 138 and 139 together. The potential applied to terminal 112 of switch Q4 is then equal to the potential applied to electrical contact 101. This causes switch Q4 to switch to its open state and then maintains switch Q4 in this open state as long as the switch Q1 is in its closed state. Switching switch Q1 to its closed state generates and transmits the insulation command on terminal 112.

Here, switch Q1 is an NPN bipolar transistor. The terminals 136, 138 and 139 therefore correspond respectively to the base, the collector and the emitter of this transistor.

Diode CR6 switches from an off state to an on state when the voltage between its cathode and its anode exceeds a threshold S3. This threshold S3 is here lower than the threshold S1. For example, threshold S3 is equal to 3.5 Vdc. In the off state, diode CR6 electrically isolates resistor R8 from electrical contact 102. Under these conditions, the voltage at point 132 is lower than threshold S2 and switch Q1 is in its open state.

In its on state, diode CR6 connects resistor R8 to electrical contact 102. The values of resistors R8 and R9 are chosen so that in this situation, the voltage at midpoint 132 is greater than threshold S2 and therefore the switch Q1 switches to its closed state.

The diodes CR4 and CR5 make it possible to make a temperature compensation of the operation of the switch Q1.

In this particular embodiment, unit 84 also includes a diode CR8 whose anode is directly connected to electrical contact 100 and whose cathode is directly connected to the cathode of diode CR1.

The operation of cylinder 12 is as follows. During a normal operating phase of cylinder 12, the voltage between electrical contacts 101 and 102 is less than or equal to threshold S1 when key 16 is introduced inside cylinder 12. Diode CR6 is therefore in its state not passing. The voltage between terminals 112 and 114 of switch Q4 is then positive and switch Q4 is maintained in its closed state. Under these conditions, the transceiver 202 and the microcontroller 200 are powered.

When the microcontroller 200 is powered, the microprocessor 218 executes, in particular, the access control module 222. During the execution of this module 222, the microcontroller 200 receives, via the electrical connection 106, the access code transmitted by the key 16 introduced inside the channel 50. The microcontroller 200 then determines whether the key 16 is authorized to unlock the cylinder 12. Here, for this, the microcontroller 200 evaluates whether the access code received is a valid access code. For this purpose, it compares the access code received with access rights prerecorded in the memory 216. If the access code received corresponds to one of these prerecorded access rights, the access code received is considered valid. The key 16 is therefore a key authorized to unlock the cylinder 12. In response, the microcontroller 200 commands the unlocking of the cylinder 12. For this, the microcontroller 200 generates on its port 286, the signal to close the switch Q9. Switch Q9 then switches to its closed state. Capacitor C3 then discharges through actuator 82. Thus, actuator 82 is powered from the electrical energy stored in capacitor C3.

When the actuator 82 is energized, it moves the blocking member 80 towards its retracted position. From then on, the user can turn the key 16 inside the cylinder 12. This rotation of the key then mechanically maintains the locking member 80 in its retracted position as long as the key 16 has not returned to its position. initial. The rotation of the key 16 causes the rotation of the bit 24 and therefore the displacement of the bolt 10 towards its retracted position. Opening of door 2 is then possible.

Conversely, if the microcontroller 200 evaluates that the access code received is invalid, the key 16 is an unauthorized key to unlock the cylinder 12. In this case, the microcontroller 200 inhibits the generation of the closing signal on port 286. This prevents the supply of the actuator 82 and therefore the movement of the locking member 80 to its retracted position. Thus, the cylinder 12 remains in its locked position.

During an abnormal operating phase, an overvoltage, for example permanent, is applied between the electrical contacts 101 and 102. The voltage between the electrical contacts 101 and 102 is then greater than the threshold S1. The voltage between the cathode and the anode of diode CR6 is then also greater than threshold S3. Diode CR6 therefore switches to its on state. The voltage at point 132 then becomes greater than threshold S2 and switch Q1 in turn switches to its closed state. This generates and transmits the isolation command on terminal 112 of switch Q4. Switch Q4 switches to its open state. The masses of the transceiver 202, of the microcontroller 200 and of the actuator 82 are now isolated from the electrical contact 101. The transceiver 202, the microcontroller 200 and of the actuator 82 are therefore protected against permanent overvoltage. present between contacts 101 and 102. Similarly, circuit 110 also protects transceiver 202, microcontroller 200 and actuator 82 against a temporary overvoltage between contacts 101 and 102

During the abnormal operating phase, the microcontroller 200 is not powered and does not operate. In particular, the microprocessor 218 cannot execute the access control module 222. Under these conditions, the microcontroller 200 cannot generate the signal to close the switch Q9, which keeps the cylinder 12 in its locked position.

In addition to what has just been described, during the normal operating phase, diode CR8 remains in its off state as long as the potential on electrical contact 100 remains less than or equal to the potential applied to electrical contact 102 Thus, in the absence of overvoltage applied between the electrical contacts 100 and 101, the diode CR8 electrically isolates the electrical connection 106 from the electrical connection 108. The electrical connection 106 can therefore be used to exchange information between the key 16 and the cylinder 12.

On the other hand, if an overvoltage is applied between electrical contact 100 and electrical contact 101, the potential at electrical contact 100 becomes greater than the potential applied to electrical contact 102. Diode CR8 then switches to its on state and connects between they the electrical connections 106 and 108. The voltage between the electrical contacts 101 and 102 then becomes equal to the voltage between the electrical contacts 101 and 100. Thus, if an overvoltage is present between the electrical contacts 101 and 100, the generator 130 generates and transmits the isolation command to terminal 112 of switch Q4. This therefore makes it possible to protect the unit 84 and, in particular, the transceiver 202 against an overvoltage, even permanent, by using for this the same protection circuit 110 as that used to protect the microcontroller 200.

Chapter II: Variants:

Other embodiments of switch Q4 are possible. For example, switch Q4 can be replaced by a switch which switches to its open state when it receives a positive voltage on its control terminal. In this case, the generator 130 is adapted to transmit this positive voltage when the threshold S1 is exceeded. For example, for this purpose, the power terminal 139 of the switch Q1 is directly connected to the electrical contact 102 instead of being connected to the electrical contact 101.

Alternatively, switch Q4 is placed between electrical contact 102 and power port 208. In this case, the insulation control generator 130 must be adapted to maintain the switch Q4 in its closed state as long as the voltage applied between the electrical contacts 101 and 102 does not cross the threshold S1.

If it is not necessary to protect the transceiver 202 and/or the actuator 82 against overvoltages, the circuit 110 can be used to protect only the microcontroller 200. In this case, the transceiver 202 and actuator 82 are directly connected to contact 101.

Other embodiments of the generator 130 are possible. For example, the Zener diode CR6 can be replaced by a Transil diode or any other type of diode capable of performing the same function.

In a simplified variant, the Zener diode CR6 is omitted and replaced by a simple lead wire. In this case, the values of resistors R8 and R9 are chosen so that the voltage at midpoint 132 exceeds threshold S2 only when the voltage between electrical contacts 101 and 102 exceeds threshold S1.

In another simplified embodiment, Zener diode CR6 is directly connected between the cathode of diode CR1 and resistor R1. In this case resistors R8, R9, diodes CR4 and CR5 as well as switch Q1 are omitted and switch Q4 is implemented as a P-type MOSFET to switch to its open state when a positive voltage is applied to its gate.

Diodes CR4 and CR5 can be omitted or replaced by any other temperature compensation mechanism for the operation of switch Q1.

In a simplified embodiment, the transistor Q5 is omitted or replaced by another electronic component which performs the same function.

Diode CR8 can also be omitted. In this case, the transceiver 202 is no longer protected against overvoltages between the electrical contacts 100 and 101.

Chapter III: Advantages of the embodiments described:

The fact of using a switch Q4 which switches to its open state when the voltage between the electrical contacts 101 and 102 exceeds the threshold S1 makes it possible to obtain a resistance vis-à-vis the permanent overvoltages much higher than those obtained by using a Zener diode. In particular, the fact that the overvoltage is present for a very long period of time does not damage the switch Q4 which then remains in its open state, thus protecting the microcontroller 200 for a prolonged period. conversely, a Zener diode resists much less time to the application of a permanent overvoltage because in this case, it is permanently crossed by a current which, over a fairly long period of time, ends up damaging it .

Moreover, if the overvoltage applied between electrical contacts 101 and 102 is such that it leads to the destruction of switch Q4, this destroyed switch Q4 remains in its open state. Thus, even if cylinder 12 is no longer usable following the destruction of switch Q4, microcontroller 200 and actuator 82 are not damaged. Cylinder 12 can therefore be restored to working order simply by replacing switch Q4. Conversely, when a Zener diode is destroyed by an overvoltage, it does not isolate the microcontroller 200 and the actuator 82 from the overvoltage applied between the electrical contacts 101 and 102. Thus, generally, the overvoltage which destroyed the Zener diode also destroys the microcontroller 200 and/or the actuator 82. It is therefore much more difficult to repair the cylinder 12.

The use of a diode to trigger the transmission of the insulation command to switch Q4 makes it possible to precisely define the value of threshold S1.

Controlling switch Q1 to transmit the isolation command to switch Q4 increases the reliability of the isolation command generator.

The fact of connecting at least one of the terminals 82A or 82B of the actuator 82 to the electrical contacts 101, 102 via the switch Q4 also makes it possible to improve the protection of the actuator 82 against overvoltages. .

The use of the diode CR8 also makes it possible to protect the unit 84 and in particular the transceiver 202 against overvoltages applied between the electrical contacts 100 and 101 and this by using the same protection circuit 110 as that used to protect the microcontroller 200 against overvoltages applied between the electrical contacts 101 and 102.

Claims (6)

Electronic lock cylinder comprising:
- a reversibly movable blocking member (80) between:
- a locking position in which it locks the electronic cylinder, and
- a retracted position in which the electronic cylinder is unlocked,
- an electric actuator (82) capable of moving the locking member from its locking position to its retracted position in response to receiving an unlocking command,
- first and second electrical contacts (101, 102) able to come directly into electrical and mechanical contact on, respectively, first and second electrical contacts of a key inserted inside the electronic cylinder, to power the electronic cylinder from a battery housed inside the key,
- a microcontroller (200) configured to determine whether the key introduced into this electronic cylinder is a key authorized to unlock this electronic cylinder and, only if so, to transmit the unlocking command to the electric actuator, this microcontroller comprising a first and a second power supply port (204, 208) electrically connected, respectively, to the first and second electrical contacts of the electronic cylinder,
- a circuit (110) for protecting the microcontroller against an overvoltage applied between the first and second electrical contacts (101, 102),
characterized in that the protection circuit (110) comprises:
- a first switch (Q4) comprising a control terminal (112) and a first and a second power terminals (114, 116), the first and the second power terminals being electrically connected, respectively, to the second electrical contact (101 ) of the cylinder and to the second power port (204) of the microcontroller, this first switch being able to switch in response to the reception of an isolation command on its control terminal:
- from a closed state in which it electrically connects the second electrical contact (101) to the second power port (204) of the microcontroller,
- to an open state in which it electrically isolates the second electrical contact from the second power supply port of the microcontroller, and
- a generator (130) of the insulation command suitable for generating and transmitting the insulation command on the control terminal of the first switch when the voltage between the first and second electrical contacts exceeds a first predetermined threshold. Cylinder according to Claim 1, in which the generator of the insulation control comprises a diode (CR6) whose cathode is connected to the first electrical contact (102), this diode being capable of switching when the voltage present between the first and second electrical contacts exceeds the first predetermined threshold:
- from a non-conducting state in which it inhibits the generation of the isolation command,
- To an on state in which it triggers the transmission of the insulation command on the control terminal of the first switch. Cylinder according to claim 2, in which the generator comprises:
- a first and a second resistor (R8, R9) connected in series between the anode of the diode (CR6) and the second electrical contact (101), and
- a second switch (Q1) comprising:
- a control terminal (136) connected to a midpoint (132) located between the first and second resistors,
- a first power terminal (139) connected to one of the first and second electrical contacts, and
- a second power terminal (138) connected to the control terminal of the first switch,
this second switching switch, when the midpoint voltage exceeds a second predetermined threshold:
- from an open state in which it inhibits the transmission of the insulation command on the control terminal of the first switch,
- Towards a closed state in which it transmits the insulation command to the control terminal of the first switch. Cylinder according to any one of the preceding claims, in which the actuator (82) comprises a first and a second supply terminal (82A, 82B) electrically connectable, respectively, to the first and second electrical contacts, the second terminal (82B ) supply of the actuator being electrically connected to the second electrical contact (101) via the first switch (Q4) of the protection circuit. Cylinder according to any one of the preceding claims, in which the first switch (Q4) is able to withstand the application of a direct voltage greater than 50 Vdc between the first and second electrical contacts (101, 102). Cylinder according to any one of the preceding claims, in which the cylinder comprises:
- a third electrical contact (100) capable of coming directly into electrical and mechanical contact with a third electrical contact of the key inserted inside the electronic cylinder, to establish an electrical connection (106) via which the cylinder and the key exchange information, and
- a diode (CR8) whose cathode is connected to the first electrical contact (102) and whose anode is connected to the third electrical contact (100).